How I learned Asp.net Core
Why I wanted to learn Asp.net Core
I was building web apps and APIs with asp.net mvc and asp.net web api respectively. The issue of these two was performance because both frameworks are built on Microsoft System.Web library so even when I wanted to build a simple web api, I have to reference System.Web which made my api to be slow when hosted. Therefore, I resulted to learning Asp.net core as soon as microsoft brought it to limelight.
Secondly, visual studio which is the only tool used in building web apps for asp.net mvc and asp.net web api was just too heavy, but asp.net core made microsoft to introduce visual studio code, a light weight, cross platform IDE for development.
How I approached learning Asp.net Core
Since I am familiar with asp.net mvc and asp.net web api framework, learning asp.net core was really not a difficult one. The difference was not that much. I learnt asp.net core from the asp.net core documentation in msdn.
Challenges I faced
One of the challenges was the tooling, unlike visual studio where you can easily reference a class library, it was challenging to reference a class library in visual studio code. Another was that most of the asp.net libraries were not yet created for asp.net core.
Asp.net core is fast in terms of performance and its cross platform, you don't need visual studio to learn or build web apps with asp.net core, visual studio code solves it.
Tips and advice
Learning asp.net core is easy. It is cross platform and visual studio code is a great tool to get you started.